Drag Reduction Characteristics Of Bionic Jet Surface

With the rapid development of economy, the energy crises are increasing day by day andit is becoming more and more imperative to carry out all the processes by consuming lessamount of energy. The energy consumption is meticulously related with the resistancebetween the mating surfaces and is widely used in a lot of fields, like ocean and rail, aviation,oil and gas pipeline etc. Drag reduction also means energy conservation and a variety of dragreduction techniques has been researched; in china as well as overseas. The research of dragreduction technology plays a key role in saving energy and improving the utilization ofexisting energy. The surface frictional resistance of an object in the fluid medium was reducedwith the method of bionic surface drag reduction in this research, which has become a hotissue in drag reduction field, and the findings of this technique will be of importance in savingenergy, increasing the utilization of energy and improving the theory system of dragreduction.This research was supported by the department of theory studies on drag reductioncharacteristic of bionic jet surface of the national natural science foundation of china(51275102), whose research was aimed at the problem of the consumption of plenty of energyexisting in the contact interface of two objects when moving relatively. Inspired by jetfunction of shark gills, based on the bionic theory, bionic jet structure model similar to the jetcharacteristic of shark gills was established; it treats the jet characteristic of shark gills asbiological prototype, in order to explore the drag reduction problem of jet surface. The dragreduction function of bionic jet was studied with the methods of theoretical analysis,numerical simulation and experimentation, which reveals the influential rules of the relevantfactors of bionic jet surface on drag reduction characteristics and clarifies the drag reductionmechanism of bionic jet.Aimed at the flow field characteristics of shark gills jet surface, the bionic jet model wasestablished with the characteristics of shark gills, and the drag reduction characteristics ofbionic jet surface were researched at a constant main flow field velocity. The jet velocityvaried in a certain range, which has got the guiding rule of the jet velocity on drag reductioneffect. The influence characteristics of bionic jet surface on the viscous resistance andpressure resistance of model wall were analyzed and the drag reduction principle of bionic jetsurface was deeply researched based on the changing situation of shearing strength andpressure stress on the wall and boundary layers.Based on the non-jet state of bionic jet surface, the bionic non-jet surface model with hemispherical pits was established to analyze the drag reduction characteristics. Aimed at theseal and friction problem between the rubber ring and barrel, the rubber sealing ring modelwith bionic non-jet surface characteristics based on the shell rubber seal of aerodynamicextinguishing cannon was established, and numerical simulation was used to research the sealand drag reduction characteristics of the rubber sealing ring of bionic non-jet surface.In consideration of the problem of flow field of bionic jet surface, the bionic jet surfacestructure model and extension model was established based on a circular jet hole. Numericalsimulation was used with the SST k-ω turbulent model in bionic jet surface model, whichanalyzed the influential principle of bionic jet surface on wall frictional resistance and dragreduction rate and exposed the control behavior of bionic jet surface on boundary layer at aconstant inlet velocity of main flow field whereas, the jet aperture and jet velocity werecoupled. Coupling elements and coupling scheme extension model of jet angle and jetvelocity were established to analyze the situation when the jet angel of bionic jet surface andjet velocity were coupled, and numerical simulation was used with SST k-ω turbulent modelin drag reduction characteristics at coupled jet angel of bionic jet surface and jet velocity. Thereason that bionic jet surface could reduce the pressure resistance and viscous resistances aswell as the control behavior of bionic jet surface on boundary layer was investigated.Coupling elements and coupling scheme extension model of main flow field velocity and jetvelocity were established to analyze the situation when the main flow field velocity of bionicjet surface and jet velocity were coupled and then numerical simulation was used with RNGk-ε turbulent model in drag reduction characteristics when the main flow field velocity ofbionic jet surface and jet velocity were coupled. the influence principle that bionic jet surfacecould affect the pressure resistance and viscous resistance was researched; the influencecharacteristics in coupling case of the bionic jet surface on drag reduction and energy savingwas analyzed; the control behavior of bionic jet surface on boundary layer of wall flow fieldnear jet aperture was clarified.Based on the test principle of coaxial rotation, the relationship between the mathematicalmodel of the frictional resistance stressed on the wall between the coaxial rotation test andplane test was established, and an experimental model was designed for gyrorotor.Experimental prototype and the data acquisition system was designed and developed to testthe drag reduction effect of bionic jet surface. The graphical user interface was written in theenvironment of LabVIEW as well as the software control of data flow. Frictional torque of thesurface against the flow of different experimental models in experiment process was acquired,and was utilized in the automation of data acquisition and the real-time of data monitor. The gyrorotor models with bionic jet surface and smooth surface were investigatedthrough the experimental prototype of bionic jet surface drag reduction test, and the contrastanalyze method was used to analyze the influence of the jet aperture, rotational speed, jetvelocity and jet angle on the frictional torque stressed bionic jet surface model and tocalculate the drag reduction effect of bionic jet surface. Meanwhile the experimental data wasanalyzed, the drag reduction characteristics of bionic jet surface were verified according to theexperimental view, and the experimental results and numerical simulation results werecompared and evaluated.